1. Field of the Invention
The present invention relates to an optical assembly with a lens magnification-adjusting function, and more particularly, to an optical assembly having tangential actuation.
2. Description of the Prior Art
In conferences, a host can project related material or graphs onto a screen with a projector to let participants better understand the discussion. However, with the advance of video/audio equipments and storage media, such as high power stereos and large capacity DVDs, families can also enjoy the same experience in a home theater through an extra-large screen and a projector in combination with a stereo sound system.
Please refer to FIG. 1. FIG. 1 is a schematic diagram of an optical assembly 10 of a projector of the prior art. The optical assembly 10 includes a barrel 12 including a spiral slot 14, a lens 16 installed inside the barrel 12 for magnifying an image, and a rod 18. The rod 18 is installed within the slot 14 of the barrel 12 in a slidable manner. The movement of the rod 18 is constrained by the slot 14 of the barrel 12 so that the magnification (zoom in/zoom out) is adjusted by the rod 18. That is, a displacement of the rod 18 consists of a combination of a tangential displacement and an axial displacement relative to the barrel 12. This kind of magnification-adjusting mechanism is very common, for example, consider many optical assemblies manufactured by Zeiss®. However, users are used to rotating the barrel 12 for adjusting magnification of the lens 16. That is, users are familiar with magnification-adjusting mechanisms requiring tangential movement of the barrel 12 instead of axial movement relative to the barrel 12. Thus, the magnification-adjusting mechanism of the optical assembly 10 does not correspond to the habits of users such that it is inconvenient for users to operate the magnification-adjusting mechanism of the optical assembly 10.